In the opening sequence we see Gorr having to bury his daughter while they get lost in a desolate wasteland. After it’s over, Gorr finds an oasis with his god there and enjoys the fruits of his labors (or lack thereof). Among the gods is a mysterious figure wielding the Necrosword. We’ll never know the name of this creature.
Many might be quick to assume that this is Knull, a sinister god of darkness and the creator of the symbiotes in Marvel Comics. He’s a pretty important character though, and it would be odd to take him down in such an unceremonious way. Ultimately, we don’t know who this being is, but it could have serious implications for the future of Marvel movies.
The Necrosword and Knull are inseparable from symbiotes in the comics, and of course that leads to the idea of Venom and Carnage making their way into the MCU proper. We already know that part of the Venom symbiote is in the MCU thanks to the post-credits scene from Spider-Man: No Way Home, so it’s possible that more symbiotes with the Necrosword are out there making their way in could find this universe.
Of course, the movie ends with the Necrosword being destroyed, but where there’s a will to include symbiotes in the MCU, there’s a way.